In the context of this article, how has America changed over time? Can Americans today relate to those who experienced the Great Depression? Why or why not? How has America’s economy evolved or improved?

Used for an event that has been completed before the present moment in time. simple past past perfect perfect progressive past perfect progressive

In a series of experiments, hershey and chase radioactively labeled dna and protein in viruses and then used labeled viruses to infect bacteria. hershey and chase's experiments definitively showed that a. dna and not protein is the genetic material. b. dna and protein work together as a cell's genetic material. c. protein and not dna is the genetic material. d. neither dna nor protein act as a cell's genetic material

This summer, stretched on well into fall, yielded a rich crop a. which b. itself c. whose d. those